Shrink-head casing for ingot molds



y 3 E. GATHMANN SHRINK HEAD CASING FOR INGOT HOLDS Filed March 8, 1

Patented May 31, 1927; v

UNITED STATES EMIL GATHMANN, or BALTIMORE, MARYLAND.

SHRINK-HEAD CASING FOR INGOT HOLDS.

Application filed March 8,

My improvements are illustrated in the accompanying drawings in which Figure 1 shows a vertical central section of an ingot mold with a mold top feeder or 5 shrink head casing applied thereto.

Figure 2 is a top plan view thereof. Figure .3 is a detailed sectional view on an enlarged scale of a part of the mold and a .part of the feeder.

The'mold A shown in the drawings, is of the well-known Gathmann type. It is supported on a stool S and has a bottom opening closed by a plug P.

The feeder or shrink head casing is made of any suitable material or kind ordinarily employed in this art and it is treated with a substance or substances which increase its insulating qualities in the manner hereinafter described. The casing may be merely coated i 2 with such substance or substances or the substance or substances may be made to impregnate the casing to a suitable de th in the manner indicated at 0. The plug may be-treated in a similar manner as indicated at p.

My invention relates to that part of a mold for casting steel ingots known as the shrink head casing or moldtop in which the upper portion of the ingot is cast and in which a pool of molten metal is maintainedduring the freezing or solidification of the ingot to supply liquid steel to the pipe or cavity formed in the ingot while solidifying. Such feeders or casings have heretofore beenusually made of refractory material such as fire brick. They have also been made of a mixture of blast furnace slagand cement and of loam and other materials, having as a ,rule lowconductivity and relatively low refractory value. When such feeders are brought into contact with the'molten metal] of forming ingots, they will to some extent melt or slag. However, such casin have been more or less efficient in delaying the freezing or solidification of'the upper portion of the molten metal until the body of the ingot has solidified and pipe formation therein prevented.

In' the use of feeders or casings heretofore employed, it has been observed that there are considerable variations in the insulating values of the material of which they are made in casings of different sizes. After. carefully considering these variations I have discovered what I believe to be the principal cause ofthe differences in the heat conserv- 1926. SeflalNo. 93,136.

ing values of large as compared with small casings. Practically all of the material used, when expense is considered, in the manufacture of heat conserving casings, has a melting point or slagging point lower than that of liquid steel at the time it is teemed or poured into the mold. In molds of 12 inches or larger horizontal cross section, and sometimes even in molds .of smaller section, it is found upon examination after solidification of the ingot body, as well asthe infgrot top, that a considerable part of the re actory casingis fused and adheres directly to the shrink head part of the ingot. Th1s causes difliculties when the steel is reheated for rolling, as the particles of the casing which have adhered to the ingot are further slagged and melted owing to the high heat of th'e'soaking pits or reheating furnaces and frequent cleaning of the pits and furnaces is required. Such molten slag, as it runs down is apt to adhere to the skin surface of the body of the ingot and cause spotty or streaklike surface decarbonization of the steel.

It is evident that the fusion of the refrac-- tory material of the casing is caused by the heat of the molten metal in the mold top. When a close contact occurs caused 'by the adhesion of the casing to the ingot top, there is a decided increase in the extraction of the heat units from the ingot.

According to my present invention, I materially improve the insulating properties of .such shrink head casings by treating them with a material, the melting point of which is higher than the temperature of molten steel. Such treatment maybe given to cas-' ings made offire cla'yfurnace slag or' other suitable materials without losing any of their good qualities while greatly increasing their efiiciency as heat insulators. In carrying out my invention, the material may be applied-to the casing by means "of a spray or brush or /by a dipping operation.- The molasses. When lime and magnesia are employed I preferably use 70 parts by weight casing may be merely coated or it may be of lime to 30-parts by weight of magnesia and a suitable quantity of water. 5

Before my invention is applied to the easings I heat them sufiiciently to drive out'any moisture which they may contain so that the coating which is applied while the casing is hot, may penetrate the casin s to the desired extent as well as effect t e drying'of the coating from the interior of the casing outwardly. v

While my improvements are applicable to practically all kinds of standard mold tops, feeders or shrink head casings, I preferably use casings made in the following manner:

Crushed blast furnace slag is mixed in a dry state with Portland cement in proportions of ten parts by weight of slag to one part by weight of cement. After the materials are thoroughly blended, they are moistened with water and the moistened mixture is thoroughly kneaded, care being taken, to use only sufiicient water to insure the moistening of the slag and cement sufiiciently to obtain a proper setting'of the cement. In this condition the material may be molded to proper shape and then dried in a hot air 0' culating furnace. Whem'the casings are thoroughly dry and while still hot, they are coated with a lime sludge or with other material similar to that hereinbefore mentioned, either by dipping, spraying or brushing. The casings are then ready for use as soon as the coating has dried.

I find it very desirable that in any case the coating for the casing should be a plied thereto while the casing is hot or a r it has been heated to the desired extent. In

- this way the moisture is driven from the sludge or the coating and there will remain -a hard coating accomplishing the purposes hereinbefore mentione I have found also that there is an advantage in treating the bottom closing plug P with the refractory material above described.

When so treated, the plug will be prevented 2. An ingot mold top or shrink head casing comprising a mixture of blast furnaceslag and Portland cement, the melting or slagging point of which is lower than the temperature of liquid steel and which has its inner walls impregnated and coated with material, the melting or slagging point of which is higher than the temperature of the liquid steel. i Y 3. an ingot mold top or'shrink head casin'g comprising a mixture of refractory material and a binder, having its inner walls impregnated and coated with a substance which prevents the deleterious action of the gas-producing constituents of the mixture and which material has a higher melting or slagging point than the temperature of liquid stee t In testimony whei eof, I have hereunto subscribed my name.

EMIL GATHMANN. 

